工作辊在冷轧过程中辊身剥落原因分析

利用ZEISS-AXIO光学显微镜、Keyence VE9800型扫描电镜和Edax能谱仪对F2冷连轧机机架工作辊轧制过程中发生剥落的原因进行了分析。结果表明:该工作辊辊身剥落是由辊身内部缺陷引起的,其剥落面宏观形貌与由辊身表面裂纹引起的剥落存在明显差异,裂纹扩展以辊身内部缺陷为圆心形成类同心圆的扩展轨迹,待扩展至一定位置后剩下部位再瞬间剥离形成剥落形貌。以类同心圆模式从辊身内部发生的剥落,其圆心裂纹源处常伴有冶金夹杂缺陷存在,夹杂物的存在会隔断轧辊本体组织的连续性而引起力学性能的降低,同时会导致轧辊内局部应力集中,为裂纹的形成和扩展提供了有利的条件。为避免该问题的发生,可进一步提高钢水的纯净度,从而降低夹杂物的形成概率。

Cause analysis on spalling of working roll during cold rolling

The spalling causes of working roll of tandem cold rolling mill housing F2 during rolling process were analyzed by ZEISS-AXIO microscope, Keyence VE9800 scanning electron microscope and Edax energy spectrometer. The results show that the spalling of the working roll is caused by the internal defects of the roll body. The macro-morphology of the spalling appearance is obviously different from the spalling appearance caused by the roll body surface cracks. The crack growth is formed at trajectory of concentric circle, which is center on the internal defect, and then the remaining parts are separated to form a spalling appearance when the cracks are extended to a certain position. The spalling occur from the inside in a concentric circle mode, and the crack source at the center of the roll often accompanied by metallurgical inclusion defects. The presence of inclusions will cut off the continuity of the roll materials and decrease its mechanical properties. Meanwhile, the local stress concentration in the roll will provide favorable conditions for the initiation and propagate of cracks. In order to avoid this problem, the purity of molten steel should be further improved, therefore, the probability of inclusion formation can be reduced.